package com.chen.pc;

// 模拟生产者和消费者问题。线程交替执行，两个线程操作同一个变量，number = 0。一个线程+1,另一个线程-1。
public class PC_synchronized {
    public static void main(String[] args) {
        Data data = new Data();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "A").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "B").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "C").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "D").start();

    }
}

// 判断等待、业务、通知
class Data {
    private int number = 0;

    // +1
    public synchronized void increment() throws InterruptedException {
        // 适用while语句判断是否需要等待，防止虚假唤醒问题
        while (number != 0) {
            // 等待
            this.wait();
        }
        // 业务
        number++;
        System.out.println(Thread.currentThread().getName() + "=>" +number);
        // 通知其它线程，+1已经完成
        notifyAll();
    }

    // -1
    public synchronized void decrement() throws InterruptedException {
        while (number != 1) {
            // 等待
            this.wait();
        }
        number--;
        System.out.println(Thread.currentThread().getName() + "=>" +number);
        // 通知其它线程，-1已经完成
        notifyAll();
    }
}
